I might suggest Fallout 3 & The Orange Box
Fallout 3 has no multiplayer but its a great horror / survival game sent in Washington D.C. after a nuclear war, there is a huge map mostly of wasteland and small towns full of raiders or mutants. Its kinda like a cross between resident evil and fable i think.
The Orange Box has 5 games in 1 disc ; Half Life 2, Half Life 2 ; Episode 1, Half Life 2 ; Episode 2, Portal and Team Fortress 2.
The half life series i still have not finished though so far it is a classic game and its a long series and should keep you occupied for a while. Portal is a game where you need to think hard to crack the puzzles and think fast in some situations when you have a little white robot turret shooting your face off and BTW "The Cake Is A Lie!"
Then theres Team fortress 2 , sure, its online only but its a good cartoon shooter and although theres not alot of online matches compared to other online games it makes up for it when you get into a match that can last up to 30 minutes if your lucky

. Although I think its better on PC as it currently has lots of unlocks thaat the 360 & Ps3 versions dont BUT Valve have said they will be releasing a update to the 360 version to puto n EVERYTHING updating into the PC version but theres no news on the Ps3, Sorry Ps3 owners! xP
EDIT: Lawl i should review games xP